No home in the galactic outer suburbs

TALK about location, location, location. If the sun had been born near the edge of the galaxy, chances are neither the Earth nor life would have arisen. That's the implication of the first search for planet-forming discs on the Milky Way's outskirts.

The stars on the fringes of our galaxy have little oxygen, silicon or iron - chief ingredients of Earth-like planets - so astronomers have long doubted that life could exist there. Now they have solid evidence for their pessimism. Chikako Yasui and Naoto Kobayashi at the University of Tokyo, Japan, and colleagues observed two extremely young star clusters in Cassiopeia 62,000 light years from the Milky Way's centre - over twice as far out as the sun - in a cloud of gas and dust named Digel Cloud 2.

The stars are only half a million years old. Most stars this young have orbiting discs of gas and ...

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